Automatic train control



April 18, 1933. D. H. SCHWEYER AUTOMATIC TRAIN CONTROL 2 Sheets-Sheet Original Filed March 27 1922 gwumtom Quanta,

Faz'llevel April 18, 1933.

AUTOMATIC TRAIN CONTROL Original Filed March 27. 1922 2 Sheets-Sheet 2 6mm wag I Patented Apr. 18, 1933 PATENT OFFICE DANIEL HEB-DEBT SCEWEYEB, OI EASE-UH, PENNSYLVANIA AUNIA'I'IO mm CONTROL Driginal application fled larch 27, 1822, Serial No. 547,087. Divided and this application fled. larch 18, 1928. Serial No. 281,275.

The present invention relates to train control apparatus, and this a plication 1s a division of my application rial No. 547,- 067 filed March 27, 1922.

5 The object of the invention is the provision, in automatic train control apparatus, of a novel relation or cooperation of alterhating and direct current circuits, wherein direct current means or devices are controlled or influenced by alternating current means, in order that the alternating current may be employed for inductive transmlssion of energy or impulses, while direct current may be employed for controlling the electromagnets or other control devices.

With the foregoing and other objects in view, which will be apparent as the description proceeds, the invention resides in t e construction and arrangement of parts, as

hereinafter described and claimed, it being understood that changes can be made within the scope of what is claimed, without departing from the spirit of the invention.

The invention is illustrated in the accompanying drawings, which depict difierent embodiments of the association of alternatinlg and direct current means, wherein igure 1 is a diagrammatical view of one form of apparatus embodying the improvements.

Fig. 2 is a diagrammatical view of a portion of said apparatus,

3 is a dlagrammatical view showing anot er form of apparatus.

Referring to F' s. 1 and 2, the train or vehicle equlpment includes a primary choke coil circuit 14 supplied continuously with varying or alternating current by an al-" ternating current generator 15 driven by a 4 steam turbine or other rime mover on the vehicle, and said circuit includes the primary winding of a step-up transformer 16 and a choke coil 17 mounted on the core 18. I

,This choke coil can be carried by the locomotive or other car or vehicle of a train at any suitable position to pass the trackdevices as will hereinafter more fully appear.

At predetermined controlling points along the track, there are provided stationary inert armatures or choke coil core sections 24 past which the choke coil core 18 moves in close proximity as the train moves alon the rails 25 of the track. As shown in Flgure 2, each armature 24 has its upper surface located in a horizontal lane spaced above the plane of the tread o the rail 25, and the choke coil passes over said armature with a suitable clearance. This arrangement provides for the closer inductive 80 relation of the choke coil with the armature 24 than with the rails or other magnetic objects on the road bed.

In the lime circuit 14 a condenser 19 is inserte of cient capacity to more than balance or neutralize the inductive reactance of the choke coil 17 under normal conditions. The capacity and inductive reactance balance one another substantially, although they are made not precisely equal Z for a purpose as will appear presently. While the train is running between the track armatures the ca acity reactanoe of the primary circuit 14 ue to the condenser 19 more than ofi'sets the inductive reactancc 7 dueto the choke coil 17 and the current and electrical force of the primary circuit are almost or practically in phase with each other.

As disclosed in the aforesaid a plication, when the choke coil passes over t e rails at a crossing or over other iron or magnetic objects on the road bed flush with the rails or lower, the inductive reactanoe will be increased slightly, and the inductive and ca- 35 pacity reactances approach or obtain an even balance, so that the impedance approaches or is closely equal to the circuit resistance. The im dance thus decreases when the choke 00' passes over a rail or similar object owing to the inductive reactance becoming equal to or nearly equal to the capacity reactance.

When the choke coil asses over a track armature 24, the air gap etween the ends of the core 18 is substantially bridged by the armature 24, thus completing a magnetic circuit of low reluctance for the choke coil and greatly increasing the inductive reactance thereof. The core 18 comes closer to the armature 24 than to the rails at a crossing or other magnetic objects on the road bed. Consequently the impedance of the primary circuit is greatly increased at this time, and the current flowing through the primary circuit is therefore markedly cut down by the track armature. The impedance in the primary circuit is thus increased from about 34 units under normal conditions to 112 units, thereby producing a considerable reduction in the flow of current through the primary winding of the transformer 16.

A direct current relay magnet 21 is controlled by the circuit 14, and to accomplish this a rectifier is operably connected between said circuit and magnet. As shown, a mechanical rectifier is employed and is connected to and operated with the generator 15 in step therewith, and such rectifier has the insulated segments 80 against which the brushes 81, 82, 83 and 84 hear. The brushes 81 and 82 continuously engage the corresponding segments and are connected to the opposite terminals of the magnet 21, while the brushes 83 and 84 which are connected to the opposite terminals of the secondary winding of the transformer 16 are alternately engaged by said segments in synchronism with the impulses given off by the generator. The connections from the secondary of the transformer through the rectifier to the magnet 21 are thus reversed in synchronism with the" opposite waves or impulses, so that a unidirectional current flows through the magnet, and when the choke coil 17 passes over the track armature 24, the considerable drop in current flowing through the circuit 14 will so reduce the current flowing through the secondary circuit, that the magnet 21 is deenergized and the switches thereof released.

The normal flow of alternating current through the primary of the transformer 16 induces a secondary current through the secondary winding of the transformer, which is rectified into direct current, and such direct current is sufiicient to insure that the switches of relay 21 will be maintained closed while the train is passing between the track armatures, whereas when the choke coil 17 passes over a track armature 24, the dropped primary alternating current due to the considerable increase in impedance, produces a drop in the secondary circuit which is proportionally greater, with the result that the relay coil or magnet 21 is deenergized at this time.

The train equipment includes an electromagnet 26 normally energized to maintain clear conditions, and this magnet is supplied with current from a generator or battery 27, which has one terminal or pole connected by a conductor 28 to one terminal of said magnet. From the magnet 26, the circuit is completed by a conductor 29, armature switch 31 under the influence of an electro-magnet 32, conductor 30', conductor 30", a second switch 41' under the influence of magnet 32, conductor 33, armature switch 34 normally held closed b the magnet 21, and a conductor 35 lea ing to the opposite terminal or pole of the battery 27. Theclear magnet 26 is therefore normally energized, and a clear lamp 36 or other signal is also kept energized by being connected in parallel with the magnet 26, to indicate clear conditions. The magnet may control any suitable means for allowing the train to proceed as usual, such as a valve 37 controling a pneumatic equipment.

A caution electro-ma et 38, normally deenergized, controls a va ve 39 or other device for producing caution conditions and allow-' ing the train to proceed below a given velocity, whereas when the magnets 26 and 38 are both deener ed this will produce danger conditions or sto ping the train. The pneumatic or other ifcvices 37 and 39 are slow acting. As far as the present invention is concerned, the devices 37 and 39 and parts controlled thereby need not be considered in detail, and they may be taken,

to represent diagrammatically any suitable means operable to automatically stop the train in case of danger conditions or to allow the train to proceed below a given velocity in case of caution track conditions. A lamp 38 or other signal is connected in parallel with the magnet 38 to indicate when caution conditions exist. One terminal of the magnet 38 is connected to the conductor 28,'and its other terminal to a conductor 40. The magnet 32 controls a third armature switch 41" normally attracted by said magnet and active when released by the magnet for connection with the conductor 40. For

completing the circuit of the caution magnet tion elements being energized upon release of switch 41" when the magnet 32 is deenergized. With this construction and arrangement it will be evident that when the train is passing between the track armatures 24 the magnet 21 is energized, switches 34 and 46 closed thereby and (assuming that the magnets 32 and 44 are in an energized state) electro-magnet 26 is energized and electro-magnet 38 is deenergized to maintain clear train conditions.

The magnet 32 (if in an energized state) is maintained energized by the train battery 27 during the periods in which the train is passing between armatures 24. The energizing circuit for this purpose comprises conductor 28 leading from the battery 27 and connected to one terminal of the magnet 32, conductor 30" leading from the other terminal of the magnet 32, switch 41 (closed), conductor 33, switch 34 (closed) and conductor 35 leading to the negative pole of the battery 27.

The magnet 44 (if in an energized state) is also maintained energized by the train battery 27 during the periods in which the train passes between the trackarmatures 24. The energizing circuit for this purpose comprises the positive conductor 28 connected to one terminal of the magnet 44, conductor 44 connected to the other terminal of the magnet, switch 43 (closed), conductor 45, switch 46 (closed) and conductor 35 leading to the negative pole of the battery 27.

When the train passes the track armatures 24 the choke coil 17 is influenced to effect the deenergization of the magnet 21, as heretofore pointed out. With this construction it will be evident that deenergization of magnet 21 in effecting the opening of the switches 34 and 46 opens the circuits to the magnets 32 and 44, and in the absence of any auxiliary holding circuits, these magnets 32 and 44 would be deenergized. Thus, the periodic deenergization of magnet 21 as the train moves over successive track armatures 24 controls the periodic deenergization of magnets 32 and 44 and therefore controls periodically the releaseof the switches 41, 31, 41" and 43.

For modifying this periodic control, auxiliary holding circuits are provided for selectively controlling the magnets 32 and 44, depending upon track conditions. The auxiliary holding circuit for magnet 32 leads from the train battery 27 and comprises the conductor 28 connected to one terminal of the magnet 32, conductor 30 leading from the other terminal of the magnet 32, switch 31 controlled by an alternating current relay 47 and conductor 35. An auxiliary holding circuit for magnet 44 also leads from the train battery 27 and comprises the conductor 28 connected to one terminal of the magnet 44, conductor 42 leading there- Clear conditions may be im ressed upon the train equipment for effecting stopping of the train, stopping of the train if the train exceeds a given-speed, and the permitting of the train to proceed at all speeds, the operation of the apparatus for efiecting this being substantially as follows:

1. Danger-If both the A. C. magnets 47 and 48 are in a deenergized state whena train passes a track armature 24, both auxiliary holding circuits for the magnets 32 and 44 are open, since the switches 31 and 41 in such holding circuits are open and since the magnet 21 is deenergized, the relays 32 and 44 are both deenergized resulting in the release or opening of the switches 41', 31, 41" and 43. When these switches are released the clear and caution magnets 26 and 38 are both deenergized and the clear and caution signals 36 and 38 are extinguished, the circuit for the Clear elements being broken by the opening of the switch 31' and the circuit for the caution elements being broken by the, release or dropping of the switch 43. The deenergization of the Clear and Caution elements brings about the automatic stopping of the train. For the further purpose of indicating a danger signal when this takes place there is further provided a danger signal 46" connected at one end to the positive conductor 28 and connected at the other end by means of the conductor 46 to the switch 43, the circuit being closed at this switch when the said switch 43 is released, completion of the circ it taking place by way of the conductor '45, witch 46 which is closed when the coil 17 has passed an armature 24 and the negative conductor 35 leading to the train battery 27. Thus, not only is the train automatically stopped but a danger signal is energized at such time.

2. Caution-If the A. C. relay 48 is energized while the A. C. relay 47 remains deenergized when a train passes an arma-- ture 24, the holding circuit for the magnet 44 is closed by the closing of the switch 41 and the holding circuit of the magnet 32 is opened by reason of the open switch 31. The holding circuit of the magnet 32 being open, the switches 41', 31' and 41" controlled thereby will drop into released position. The holding circuit for the magnet 44 being closed, switch 43 will remain in attracted position, as shown in Figure 1.

The' release of the switches 41', 31' and trol elements 36 and 26 is opened when the switch 31' is released, the caution elements 38 and 38 being energized by reason of the connection between the switch 41" and the conductor 40 when the said switch is moved to released position. The circuit to the cantion elements when this occurs may be traced as follows: conductor 28, the caution elements 38 and 38 in parallel, conductor 40, released switch 41", conductor 42', conductor 44', switch 43 (closed), conductor 45,

switch 46 (closed after the train passes the armature 24) and conductor 35 leading to the battery 27. Thus, under these conditions, the caution elements are energized and the clear elements deenergized, the train being automatically stopped b any suitable mechanism if it exceeds a pre etermined velocity, and being permitted to pass on if movlng below the said predetermined velocity. The speedcontrol means may be of any suitable kind and forms no art of the present invention. It will be urther noticed that the energization of the magnet 44 and the sustaining of the switch 43 prevents the danger signal 46" from being energized at this time.

3. Clear When the A. C. magnet 47 is energized and the A. C. magnet 48 remains in a deenergized state when the train passes over an armature 24, this condition of affairs being illustrated in the diagrammatic representation of Figure 1, the holding circuit for the ma net 32 is closed while the holding circuit for the magnet 44 is open, this magnet 44 being, however, energized by reason of the energization of the magnet 32 for eifectin the positioning of the parts, as shown in %igure 1.

With the parts so positioned the Clear elements 26 and 36 are energized, the Caution elements remain deenergized and the danger signal 46" remains Out indicating clear track conditions. The energization of the Clear elements 36 and 26 is obtained by the following closed circuit: conductor 28 through the clear elements 26 and 36 in parallel, conductor 29, switch 31' (closed), conductor 30, conductor 30, switch 41 (closed), conductor 33, switch 34 (closed when the train asses beond the armature 24), and con uctor 35.

he caution elements rem'ain deenergized by reason of the fact that the circuit of said caution elements is open between the switch 41" and conductor 40. The danger signal 46 remains deenergized by reason of the fact that the switch 43 is sustained b the energized magnet 44, said magnet 44 eing energized by the following circuit: conductor 28, magnet 44, conductor 42', switch 41" and conductor 35 leading to the train battery 27.

The A. C. magnets 47 and 48 for afiecting and influencin the train equipment for efiecting the a ove operations are, in turn, controlled by track conditions. Thus, the magnet 47 has its coil disposed in a secondary circuit 64 including an inductance coil 53 on a core 50. The circuit 64 includes a condenser 65 which is shown in series with the magnet, although it can be connected in shunt or parallel with such magnet or both series and shunt connections may be provided. The magnet 48 is similarly disposed in a secondary circuit 66 with an inductance coil 55 disposed on a core 52, and such circuit may include the condenser 67 in series with or in shunt or parallel (or both) with the magnet. The condensers 65 and 67 are used in the corresponding circuits for neutralizing the inductive rcactance. The circuits 64 and 66 receive electrical current by induction from the track devices, which in turn receives its current by induction from the vehicle devices. The vehicle equipment includes an inducing coil 54 disposed 111 the circuit 62 with the alternating current generator 15, which circuit also includes the condenser 63 for neutralizing the inductive reactance. The coil 54 is disposed on a core 51. fluctuating or varying current rom the generator 15 for inducing current in the track device.

The track device includes three coils 59, 60 and 61 disposed on the respective cores 56, 57 and 58, and the arrangement is such that when the coil 17 passes over the armature 24, the cores 50, 51 and 52 of the vehicle equipment pass substantially simultaneously over the cores 56, 57 and 58, respectively, of the track device, as seen in Figure 1. The core 57 thus completes a magnetic circuit with the core 51, so that the magnetic flux passing through the core 57 from the core 51 will induce a secondary current in the inductance coil 60, and from the coil 60, the current can be passed selectively through the coils 59 and 61. If the coil 59 is energized it will induce current in the coil 53, the magnetic flux passingfromi the core 56 to the core 50. If the c011 61 is energized by the fluctuating current from the coil 60, the magnetic flux passing from the core 58 through the core 52 will energize the inductance coil 55. The coil 60 is thus energized from the coil 54 and the coils 53 and 55 are energized from the respective coils 59 and 61, with the source of electrical energy on the train or vehicle. The switches 31 and 41 are normally open, with the magnets 47 and 48 dead, and the closing of the switches 31 and 41 is controlled by the energization of the coils 53 and 55 respectively from the coils 59 and 61.

The coil 54 is thus ener 'zed by the.

In order to control the vehicle equipment forclear, caution and danger or other conditions, the track device includes a conductor 68 to which one terminal of each of the coils 59, and 61 is connected, andthe other terminal of the coil*60 is connected through a condenser 69 to a three position switch which in the present embodiment of my invention comprises a track electromagnet 71 disposed in a suitable track circuit in which the current can be made to flow in either direction by any suitable means which will be apparent to those skilled in the art. A neutral switch and a polarized armature switch 73 are under the influence of said magnet, the latter having a. contact 72 against which the switch 70 bears when the magnet is energized with the current flowing in either direction. The switch 73 alternately bears against contacts 74 and 75 which are connected by the respective conductors 76 and 77 with the coils 59 and 61. The switch 73 is polarized so that when the current flows through the magnet 71 in one direction, the switch 73 will be moved against the contact 74, whereas when the current is reversed, the switch 73 will be moved against the contact 75 owing to the change in polarity of said magnet. When the ma et 71 is deenergized, the switch 70 will magnet 71 is energized to move the switch 73 against the contact 74 and the switch 70 against the contact 72, a circuit is closed including the coil 60, condenser 69, switch 70, switch 73 and conductor 76. Conseuently, the current induced in the coil 60 om the coil 54, while the train or vehicle assing the controlling point of the trac will be reinduced to the vehicle equipment from the coil 59 to the coil 53, thereby energizing the ma net 47 and attracting the switch 31 to close the connection between the conductor 30 and 35. Should the magnet 71 be energized by the flow of current in the opposite direction, so that the switch 73 engages contact 75, the circuit will now include the coil 60, condenser 69, switch 70, switch 73 and conduc tor 77 so that the coil 55 would be energized from the coil 61 when current is induced in the coil 60. Consequently, the magnet 48 would be energized to close the switch 41. Should the magnet 71 be deenergized, the opening of the switch 70 would disconnect both coils 59 and 61 from the coil 60, so that the inducing coils 59 and 61 would not be energized even though the coil 60 is energized from the coil 54. Three conditions of control are thus obtained by the reversing of the polarized switch 73 and the opening of the switch 70.

In addition to the condenser 69, condens ers can be connected in shunt with the coils 59 and 61 to neutralize the inductive reacopened. When the tance, and several coils 59 and 61 can be used connected in series or in parallel.

A clearing switch 49 is connected between the conductors 35 and 49', and is normally open; This switch, when closed, will energize the magnets 32 and 44 connecting the magnet 32 with the con uctor 35 even though the switches 41', 34 and 46 are open.

The operation of the apparatus is as follows: The primar circuit from the generator 15 through t e transformer 16, choke coil 17 and condenser 19, will of course be energized by normal current flow whenever the train is passing between the armatures 24. As stated above, the capacity, under such conditions practically neutralizes the inductive reactance of the coil 17 in such-a way as to permit a current of relatively highvalue to pass through the circuit. Moreover, when the 'coil 17 passes over rails or other objects at crossings and elsewhere,

the impedance may even be decreased as hereinbefore explained, to increase the current flow in the circuit, and therefore cause the switches34 and 46 to stick more tightly against their contacts by the added energization of the ma-gnet'or relay 21. Such magnet is switches thereof closed by the induced current through the secondary of the transformer 16. Under normal running conditions, the magnets or relays 32 and 44 will also be energized and the switches thereof closed while the train or vehicle is travelling between the track armatures, or in starting, the switch 49 may be temporarily thrown in to close the circuits throu 44 from the battery or source of electrical energy 27. Thus, by closing the switch 49, a circuit is closed including the battery 27, conductor 28, magnet 32, conductor 49', switch 49 and conductor 35, thus energizing magnet 32. Magnet 44 is energized by the circuit conductor 28, magnet 44, conductor 42',- switch 41" (closed by energization of magnet 32) and conductor 35. The magnet or coil 21 being energized will attract and close the switches 34 and 46 for energizing the magnets 32 and 44 independently of the switch 49, the said switch 49 being thereafter opened. The magnets 32 and 44 having been energized by the closing of the switch 49, it will be apparent, as hereinbefore described in detail, that the closing of the switches 34 and 46 will connect the magnets 32 and 44 in circuits energized from the battery 27, the switches 41', 31', 41" and 43 being closed, as shown in Figure 1 of the drawings for producing clear vehicle conditionS. magnets 47 and 48 are normally open.

When the train or vehicle passes a congh the coils 32 and therefore kept energized and the trolling point of the track, with the coil 17 passing over a track armature 24, the inthe current flowing from the generator throu h the primary of the transformer 16, and-this change in current is intensified by the transformer action to roduce a drop in current in the secondary circuit of the transformer, which will insure that the relay or magnet 21 will release its armature switches .34 and 46. Thus, the circuits for the magnets or coils 32 and 44 through the res ective armature switches 41' and 43, wil be broken each time the train passes a track armature, and such magnets 32 and 44 will remain deenergized after assing the track armature, unless the auxi iary circuits are established.

The auxiliary circuits for the magnets 32 and 44 are controlled by the A. C. magnets 47 and 48, and as deta ledhereinbefore, when the said magnets 47 and 48 are dead when the train passes the armature 24, the magnets 32 and 44 are both deenergized, producing a stopping of the train; -and when the A. C. magnet 48 is energized while the magnet 47 is dead When the train passes an armature 24, caution train conditions will be obtained and further when the magnet 47 is energized while the magnet 48 is dead when the train passes an armature 24 clear train conditions are obtained, as diagrammatically indicated in Figure 1. The first or danger condition is obtained when the track magnet 71 is deenergized and the switch opened, the coils 59 and 61 both remaining passive or inactive when current is induced in the track coil 60 from the train coil 54 by the passage of the train. Consequently, the switches 31 and 41 will remain open, the auxiliary holding circuits for magnets 32 and 44 being thereby opened, the passage of the train at this time over the track armature 24 deenergizing the magnets 32 and 44 and effecting stopping of the train and energizing the danger signal 46". For influencing the train equipment to obtaincaution conditions the magnet 71 is energized by the flow of current therethrough in a given direction to move the switch 73 against the contact and the switch 70 against the contact 72. Now, when the train passes the controlling point, and the magnet 21 is deenergized to permit the switches 34 and 46 to open, the switch 31 will remain open because the coil 53 does not receive an impulse fromthe track device, whereas the receiving coil 55 receives an impulse by induction from the coil 61, thereby energizing the magnet 48 and attracting and closing the switch 41. The closing of the switch 41, as hereinbefore detailed completes the auxiliary circuit for energizing the magnet 44, the caution elements 38 and 38 being energized by the closing of the switch 43 and the dropping of the switch 41", the latter being obtained by the deenergization of the magnet 32. The clear train conditions are obtained by clear track conditions when the track magnet 71 is energized by current flo'win in the opposite direction to attract the po arized armature 73 for contact with the conductor 74 and the armature 70 for connection with the contact 72, this resulting in connecting the coils 59 and 60 in circuit. The inducing coil 54 is continually energized with fluctuating current from the generator 15 so that when the coil 17 passes over the armature 24 the flux in the core 51 of the coil 54 passes through the core 57 .of the track receiving coil 60, thereby inducinf a current in the circuit of the coil 60 inclu. ing the inducing coil 59. The fluctuating current in the coil '59 will, in turn, induce a current in the coil 53 so that the current'which originates from the vehicle is induced or reflexed back from the track device to the vehicle device to energize the magnet 47 and attract the switch 31 for closing the auxiliary holding circuit for the magnet 32. The A. C. magnet 48, however, is not energized and remains dead, its switch 41 remaining thereb open, the positioning of the parts being e ected as shown in Figure 1 of the drawings for obtaining clear vehicle conditions.

The auxiliary holding circuits for the magnets 32 and 44 are effective only when the train coils 53, 54 and 55 pass the track coils 59, 60 and 61, this being obtained substantially during the time of the passage of the choke c011 17 over an armature 24. However, as soon as the train passes a controlling point of this kind the conditions impressed upon the magnets 32 and 44 by the train and track induction coils 53 to 55 and 59 to 61 are maintained when the choke coil 17 passes entirely over an armature 24, effecting the energization of the magnet 21 and the closing of the switches 34 and 46. When danger conditions are impressed upon the train equipment, however, the switch 49 must first be closed by the operator or engineer before proceeding with train movement. After the train induction coils have passed the track induction coils the magnets 47 and 48 are both dead and the auxiliary holding circuits for the magnets 32 and 44 are both open, the control of these magnets being then under the influence only of the periodically controlled magnet 21.

A three condition or point control is thus obtained, and each time the train passes a controlling point, the magnet 21 is deener gized. to place the train equipment in danger condition unless this is prevented by the reinduction of current from the track device. If the track magnet 71 is dead, neither of the magnets 47 or 48 will receive current, and the train equipment will go to danger by the opening of the switches 34 and 46, rendering all of the magnets 26, 32, 38 and 44 dead. The 'energization of the receivin coil 53 of the train equipment from the coil 59 of the track device, on the one hand, will give a clear si 9.1, or indication when passing the controlling point, and the energization of the receiving coil 55 from the coil 61 ofthe track will produce a caution condition as above described. If a two condition or point controlonly is wanted, the a paratus can be simplified considerably.

or example, this would eliminate the coil 55, core 52, circuit 66, magnet 48, 67, switch 41, conductor 42, ma ets 38 and 44, lamp 38', conductor 40, swltch 43, conductor 45 and switch 46. In the track device, the coil61 and core 58 can be eliminated for such two condition control, and the magnet 71 would simply operate a make and break switch 70 between the coils 59 and 60. Consecpliently, if the coil 59 were energized from t e c011 by the closing of the relay switch, the current would be induced in the magnet 47 when passing a controlling point to close the switch 31'and keep the magnets 32, and 26 energized when the magnet 21 was deenergized, whereas if the coil 59 were disconnected from the coil 60, the magnet 47 wouldremain dead and the switch 31 would ,remain open, so that the magnets32 and 26 would become dead, thereby giving a danger signal or indication accordingly.

Figure 3 shows the use of dlrect current or neutral electr -magnets 47 and 48' in lieu of the alternating current magnets 47 and 48 in connection with audions or amplifiers and 67 respectively. A direct current or neutral electromagnet 21" is also used, in connection with an audion or amplifier 90. The primary circuit 14 isthe same as hereinbefore described, and the secondary winding of the transformer 16 has one terminal connected b a conductor 20 with the grid 91 of the audion 90, and has its other terminal connected to the conductor 35 leading to the direct current generator 27 ()ne terminal of the magnet 21 is connected to the conductor 28 and the other terminal is connected to the plate 92 of the audion. The filament 93 of the audion is connected in circuit with the battery 94 and rheostat or vari able resistance 95, and one terminal of said filament is also connected to the conductor 35. The filament 93 is energized by current from the battery 94, and the alternating current induced by the tranformer 16 creates a state of ionization within the audion 90 for the flow of current from the generator 27 through the audion and magnet 21. Thus, the secondary current flowing through the secondary of the transformer passes through the ionized gas of the audion 90 between the filament 93 and grid 91, which decreases the resistance between the filament 93 and plate condenser 92. Consequently, the current from the generator 27 can flow through the conductor 35, filament 93, gas of the audion, plate 92, magnet 21' and conductor 28, for energizing said magnet and holding the switches 34 and 46 closed under normal running conditions. However, when the choke coil 17 passes over a track armature 24, the increased impedance in the circuit 14 will cause a considerable drop in current in said circuit and also in the secondary circuit, thereby decreasing the fiow of current from the transformer between the filament. 93 and grid 91 of the audion. This will considerably increase the resistance of the audion in the circuit of the magnet 21', causing said magnet to be deenergized so as to release the switches 34 and 46. Such switches are therefore opened each time that the choke coil passes a track armature, the same as in the arrangement as shown in Figure 1. f

The switches 31 and 41 control the circuits of the magnets 32 and 44 in substantially the same way as shown and described in connection with Figure 1. In fact, the circuits of the magnets 32, 26, 44 and 38 are the same as in Figure 1, only the control of the magnets 21', 47' and 48' being difi'erent. The magnets 47 and 48' are controlled by the corresponding audions or amplifiers 65' and 67 respectively. One terminal of each of the receiving coils 53 and 55 of the vehicle equipment is connected to the conductor 35, and the other terminals of said coils are connected by the respective conductors 64 and 66, with the corresponding grids 100 and 105 of the audions 65 and 67 The filament 102 of the audion 65 is connected in circuit with the battery 103 and the rheostat'of variable resistance 104, and one terminal of the filament 102 is also connected to the conductor 35. One terminal of the magnet 47 is connected to the conductor 28 and the other terminal isconnected to the plate 101 of the audion 65. Similarly, the filament 107 of the audion 67 is connected in circuit with the. battery 108 and rheostat 109, with one terminal of the filament connected to the conductor 35. The plate 106 of the audion 67 is connected to one terminal of the magnet 48 and the other terminal of said magnet isconnected to the conductor 28.

The intermediate coils 54 and 60 of the vehicle and track devices are eliminated, in this arrangement, and the track device is silghtly different, although it uses the polorized relay including the electro-magnet 71, polarized armature switch 73 and neutral switch 70. The coils 59 and 61 are connected by a conductor 68, and conductors 76 and 75 lead from the other terminals of the respective coils 59 and 61 to the contacts 74 and 75, while a battery 69' is connected between the conductor 68 and switch 70.

When the magnet 71 is energized by current flowing therethrough in one direction, the switch 73 contacts with the contact 74, and the switch bears against the contact 72, thereby connecting the battery 69 with the coil 59, whereas when the current flows through the magnet '71 in the opposite direction, the coil 61 is now connected in circuit with the battery 69. When the magnet 71 is deenergized, the switch 70 opens to disconnect both coils 59 and 61 from the battery, thereby obtaining a three condition control.

The operation of this modified arrangement is substantially the same as the apparatus shown in Figure 1, excepting that the magnets 21, 47 and 48 are controlled through the audions and corresponding elements. When the vehicle or train passes a controlling point, as above indicated, the audion 90 increases the resistance to the fiow of current through the circuit including the magnet 21', whereby said magnet is deenergized and the switches 34 and 46 are opened during such interval, when the choke coil 17 is over the armature 24. If both coils 59 and 61 are dead, then the switches 31 and 41 will remain open, so that the train equipment will go to'danger. Ordinarily, the filaments 102 and 107 of the audions 65 and 67' respectively are energized, but the gas of said audions will provide sufficient resistance in the circuits of the magnets 47 and 48 to prevent said magnets from being energized. The magnet 47' is disposed in the circuit including the generator 27, conductor 28, magnet 47, plate 101, filament 102, and conductor 35, while the magnet 48' is disposedin a similar circuit including the generator 27, conductor 28, magnet 48', plate 102, filament 107 and conductor 35. For clear conditions, if the switch 73 is against the contact 74 and the switch 70 closed, the coil 59 is energized from the battery 69', and when the controlling point is being passed, the coil 53 will receive an impulse from the coil 59 when the cores 50 and 56 register, while the choke coil 17 is passing over the armature 24. The electrical impulse in the receiving coil 53 will pass through the gas of the audion 65 by way of the conductor 64, grid.100, filament 102 and conductor 35, and the ionization of the gas of said audion will decrease the resistance between the plate 101 and filament 102 so that current can flow from the generator 27 through the magnet 47 thereby energizing said magnet and closing the switch 31 during the interval that the switches 34 and 46 are opened. This will maintain the magnet 32 energized, as described in connection with Figure 1. Under caution conditions, with the switch 73 a ainst the contact 75, and the switch 70 cosed, the coil 61 is energized from the battery 69', so that the receiving coil 55 and audion 67' will receive the electrical impulse. The switch 31 will remainopen, while the switch 41 will be closed. The impulse received by the coil 55 passes through the audion by way of the conductor 66', grid 105, filament 107 and conductor 35, thereby ionizing the gas of said audion and decreasing the resistance between the plate 106 and filament 107, so that the magnet 48 is energized to attract and close the switch 41. Consequently, as hereinbefore described, in connection with Figure 1, the magnet 44 will be energized while the magnet 32 will be deenergized after passing the controlling point, to produce caution conditions. A clearing switch 49 is also shown between the conductors 49 and 35, for enabling the magnets 32 and 44 to be again energized by an authorized person, after a caution or danger signal has been given.

In either arrangement, failure of current in either the vehicle equipment or track device will result in the apparatus giving a danger signal or condition, and if the danger condition'created atintervals when the choke coil passes the track armatures is not modified by the activity of the clear or caution devices, then a danger condition will remain, either intentionally or accidentally, after passing the controlling point, by reason of a signal impulse received by the vehicle equipment or a failure of th apparatus.

In order to prevent the armatures 24 from being removed without detection, each armature 24, as seen in Figure 1, can be bridged across insulation 25 in the corresponding rail, by connections 24' between the rail sections and armature, so that said armature will constitute a part of a track circuit. With this arrangement, if the armature is removed, the track circuit will be opened, and this can be taken advantage of to enable the defect in the track equipment to be detected.

It is understood that pulsating, fluctuating or other current may be used in lieu of and under the general designation of alternating current.

Having thus described the invention, what is claimed as new is 1. In automatic train control apparatus, vehicle-carried alternating current inductive means controlled from the trackside and including a generator for energizing said means, a direct current control element, and an electrical connection between said means and element including a transformer and a full wave mechanical rectifier driven with the generator in order that said element be sensitive in response to variations in the energization of the first-named means.

2. In an automatic train control apparatus, an electro-pneumatic valve, a source of current for energizing said valve, and a direct current actuated electro-magnetic relay controlling the application of said current source to said electro-pneumatic valve, an inductive circuit in which alternating current flows in accordance with trackway control, and a rectifier for translating said alternating current into direct current for actuating said relay to o erate said electro' pneumatic valve in accor ance with the flow of alternating current in said inductive circuit.

3. In an automatic train control apparatus, an electro-pneumatic valve, a source of current for energizing said valve, and a direct current actuated electro-magnetic relay controlling the application of said current source to said electro-pneumatic valve, an inductive circuit in which alternating current flows in accordance with trackway control, and a full wave rectifier for translating said alternating current into direct currentfor actuating said relay to operate said electro-pneumatic valve in accordance with the flow of alternating current in said inductive circuit.

4. In automatic train control apparatus, a primary circuit on the train including an A. C. generator and the primary winding of a transformer, said circuit bein subject to current fluctuations in accor ance with trackway control, a secondary circuit which includes a direct current control element and means furnishing direct current for energizing said control element in accordancewith trackway control of said primary circuit, said means comprising a secondary transformer winding inductively coupled with said primary transformer winding and a full wave rectifier driven with the generator.

5. In automatic train control apparatus, a primary circuit on the locomotive which includes an A. C. enerator, the primary winding of a trans ormer, and a choke coil in series therewith, said choke coil havin an open core, means periodically disposed a ong the trackway, each of WlllCll may constitute a magnetic bridge for the gap of said open core at the time the locomotive passes, thus increasing the impedance of the coke winding and suppressing the normal current flow through the primar circuit, and a secondary circuit which inc udes a direct current control element and means for energizing said control element in accordance with said trackway means and translating a suppression of the normal flow of current in said primary circuit as a substantial interruption of the direct current energizing said control element, said control element energizing means comprising a secondary transformer winding inductively coupled with said primary transformer winding and a commutating device driven in synchronism with the generator for complete rectifica tion of currents induced in said secondary winding.

6. In automatic train control apparatus, a primary circuit on the train including an A. 0. generator and the primary winding of a transformer, said circuit being subject to trol, a source of current for energizin said" elecmeans, and a direct current actuat tro-magnetic relay controlling the application of said current source to said means, an inductive circuit in which alternating current flows in accordance with trackway control, and a rectifier for translating said alternating current into direct current for actuating said relay to effect energization of said locomotive carried means in accordance with the flow of alternating current in said inductive circuit.

8. In an automatic signal system for vehicles, indicating-means, a source of current for energizing said indicating means, and

a direct current actuated electro-magnetic relay controlling the application of said current source to said indicating means, an inductive circuit in which alternating current flows in accordance with trackway control,and a rectifier for translating said alternating current into direct current for actuating said relay to operate said indi cating means in accordance with the flow of alternating current in said inductive circuit. H

9. In a signal system for vehicles, a translating device, a source of current for energizing said translating device, a direct current actuated electro-magnetic relay controlling the application of said current source to said translating device, an inductive circuit in which alternating current flows in accordance with trackway control and a full wave rectifier for translating said alternating current into direct current for actuating said relay to operate said translating device in accordance with the flow of alternating current in said inductive circuit.

10. In an automatic'signal system for vehicles, means carried by the vehicle for actuation in accordance with trackway control, a source of current for energizing said means, and a direct current actuated electro-magnetic relay controlling the applica tion of said current source to said means, an inductive circuit in which alternating cur- 5 rent flows in accordance with trackway control, and a rectifier for translating said alternating current into direct current for actuating said relay to effect energization of said vehicle carried means in accordance 10- with the flow of alternating current in said inductive circuit. In testimony whereof 1 hereto afiix my signature.

DANIEL HERBERT SOHWEYER. ll w 

